"use strict";

// let IntervalTree = require('flatten-interval-tree');
import IntervalTree from '@flatten-js/interval-tree';
import * as Intersection from '../algorithms/intersection';
import Flatten from '../flatten';

export class Distance {
    /**计算点之间的距离和最短线段
     * Calculate distance and shortest segment between points
     * @param pt1
     * @param pt2
     * @returns {Number | Segment} - distance and shortest segment
     */
    static point2point(pt1, pt2) {
        return pt1.distanceTo(pt2);
    }

    /**计算点与线之间的距离和最短线段
     * Calculate distance and shortest segment between point and line
     * @param pt
     * @param line
     * @returns {Number | Segment} - distance and shortest segment
     */
    static point2line(pt, line) {
        let closest_point = pt.projectionOn(line);
        let vec = new Flatten.Vector(pt, closest_point);
        return [vec.length, new Flatten.Segment(pt, closest_point)];
    }

    /**计算点与圆之间的距离和最短线段
     * Calculate distance and shortest segment between point and circle
     * @param pt
     * @param circle
     * @returns {Number | Segment} - distance and shortest segment
     */
    static point2circle(pt, circle) {
        let [dist2center, shortest_dist] = pt.distanceTo(circle.center);
        if (Flatten.Utils.EQ_0(dist2center)) {
            return [circle.r, new Flatten.Segment(pt, circle.toArc().start)];
        } else {
            // 绝对值
            let dist = Math.abs(dist2center - circle.r);
            let v = new Flatten.Vector(circle.pc, pt).normalize().multiply(circle.r);
            let closest_point = circle.pc.translate(v);
            return [dist, new Flatten.Segment(pt, closest_point)];
        }
    }

    /**计算点与线段之间的距离和最短线段
     * Calculate distance and shortest segment between point and segment
     * @param pt
     * @param segment
     * @returns {Number | Segment} - distance and shortest segment
     *
     * 点到直线的距离
     * https://blog.csdn.net/gyjllll/article/details/136140761
     * 空间点到空间三角形的最近距离
     * https://wenku.baidu.com/view/3f044cb6c2c708a1284ac850ad02de80d4d80692.html?_wkts_=1728953610647&bdQuery=%E4%B8%89%E8%A7%92%E5%BD%A2+%E5%9E%82%E7%BA%BF%E8%B7%9D%E7%A6%BB+%E4%BD%BF%E7%94%A8%E5%90%91%E9%87%8F%E5%8F%89%E7%A7%AF%E8%AE%A1%E7%AE%97&needWelcomeRecommand=1
     */
    static point2segment(pt, segment) {
        /* Degenerated case of zero-length segment */
        if (segment.start.equalTo(segment.end)) {
            return Distance.point2point(pt, segment.start);
        }

        let v_seg = new Flatten.Vector(segment.start, segment.end);
        let v_ps2pt = new Flatten.Vector(segment.start, pt);
        let v_pe2pt = new Flatten.Vector(segment.end, pt);
        let start_sp = v_seg.dot(v_ps2pt);
        /* dot product v_seg * v_ps2pt */
        let end_sp = -v_seg.dot(v_pe2pt);
        /* minus dot product v_seg * v_pe2pt */

        let dist;
        let closest_point;
        if (Flatten.Utils.GE(start_sp, 0) && Flatten.Utils.GE(end_sp, 0)) {    /* point inside segment scope 分段范围内的点 */
            let v_unit = segment.tangentInStart(); // new Flatten.Vector(v_seg.x / this.length, v_seg.y / this.length);
            /* unit vector ||v_unit|| = 1 */
            // 正弦定理 sinA = H / b
            // https://baike.baidu.com/item/%E6%AD%A3%E5%BC%A6%E5%AE%9A%E7%90%86/2657575?fr=ge_ala
            dist = Math.abs(v_unit.cross(v_ps2pt));
            /* dist = abs(v_unit x v_ps2pt) */
            closest_point = segment.start.translate(v_unit.multiply(v_unit.dot(v_ps2pt)));
            return [dist, new Flatten.Segment(pt, closest_point)];
        } else if (start_sp < 0) {                             /* point is out of scope closer to ps 点超出范围，更接近ps */
            return pt.distanceTo(segment.start);
        } else {                                               /* point is out of scope closer to pe 点超出范围，更接近于pe */
            return pt.distanceTo(segment.end);
        }
    };

    /**
     * Calculate distance and shortest segment between point and arc
     * @param pt
     * @param arc
     * @returns {Number | Segment} - distance and shortest segment
     */
    static point2arc(pt, arc) {
        let circle = new Flatten.Circle(arc.pc, arc.r);
        let dist_and_segment = [];
        let dist, shortest_segment;
        [dist, shortest_segment] = Distance.point2circle(pt, circle);
        if (shortest_segment.end.on(arc)) {
            dist_and_segment.push(Distance.point2circle(pt, circle));
        }
        dist_and_segment.push(Distance.point2point(pt, arc.start));
        dist_and_segment.push(Distance.point2point(pt, arc.end));

        Distance.sort(dist_and_segment);

        return dist_and_segment[0];
    }

    /**计算线段与直线之间的距离和最短线段
     * Calculate distance and shortest segment between segment and line
     * @param seg
     * @param line
     * @returns {Number | Segment}
     */
    static segment2line(seg, line) {
        let ip = seg.intersect(line);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];   // distance = 0, closest point is the first point
        }
        let dist_and_segment = [];
        dist_and_segment.push(Distance.point2line(seg.start, line));
        dist_and_segment.push(Distance.point2line(seg.end, line));

        Distance.sort(dist_and_segment);
        return dist_and_segment[0];

    }

    /**
     * Calculate distance and shortest segment between two segments
     * @param seg1
     * @param seg2
     * @returns {Number | Segment} - distance and shortest segment
     */
    static segment2segment(seg1, seg2) {
        let ip = Intersection.intersectSegment2Segment(seg1, seg2);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];   // distance = 0, closest point is the first point
        }

        // Seg1 and seg2 not intersected
        let dist_and_segment = [];
        let dist_tmp, shortest_segment_tmp
        [dist_tmp, shortest_segment_tmp] = Distance.point2segment(seg2.start, seg1);
        dist_and_segment.push([dist_tmp, shortest_segment_tmp.reverse()]);
        [dist_tmp, shortest_segment_tmp] = Distance.point2segment(seg2.end, seg1);
        dist_and_segment.push([dist_tmp, shortest_segment_tmp.reverse()]);
        dist_and_segment.push(Distance.point2segment(seg1.start, seg2));
        dist_and_segment.push(Distance.point2segment(seg1.end, seg2));

        Distance.sort(dist_and_segment);
        return dist_and_segment[0];
    }

    /**
     * Calculate distance and shortest segment between segment and circle
     * @param seg
     * @param circle
     * @returns {Number | Segment} - distance and shortest segment
     */
    static segment2circle(seg, circle) {
        /* Case 1 Segment and circle intersected. Return the first point and zero distance */
        let ip = seg.intersect(circle);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        // No intersection between segment and circle

        /* Case 2. Distance to projection of center point to line bigger than radius
         * And projection point belong to segment
          * Then measure again distance from projection to circle and return it */
        let line = new Flatten.Line(seg.ps, seg.pe);
        let [dist, shortest_segment] = Distance.point2line(circle.center, line);
        if (Flatten.Utils.GE(dist, circle.r) && shortest_segment.end.on(seg)) {
            return Distance.point2circle(shortest_segment.end, circle);
        }
        /* Case 3. Otherwise closest point is one of the end points of the segment */
        else {
            let [dist_from_start, shortest_segment_from_start] = Distance.point2circle(seg.start, circle);
            let [dist_from_end, shortest_segment_from_end] = Distance.point2circle(seg.end, circle);
            return Flatten.Utils.LT(dist_from_start, dist_from_end) ?
                [dist_from_start, shortest_segment_from_start] :
                [dist_from_end, shortest_segment_from_end];
        }
    }

    /**
     * Calculate distance and shortest segment between segment and arc
     * @param seg
     * @param arc
     * @returns {Number | Segment} - distance and shortest segment
     */
    static segment2arc(seg, arc) {
        /* Case 1 Segment and arc intersected. Return the first point and zero distance */
        let ip = seg.intersect(arc);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        // No intersection between segment and arc
        let line = new Flatten.Line(seg.ps, seg.pe);
        let circle = new Flatten.Circle(arc.pc, arc.r);

        /* Case 2. Distance to projection of center point to line bigger than radius AND
         * projection point belongs to segment AND
           * distance from projection point to circle belongs to arc  =>
           * return this distance from projection to circle */
        let [dist_from_center, shortest_segment_from_center] = Distance.point2line(circle.center, line);
        if (Flatten.Utils.GE(dist_from_center, circle.r) && shortest_segment_from_center.end.on(seg)) {
            let [dist_from_projection, shortest_segment_from_projection] =
                Distance.point2circle(shortest_segment_from_center.end, circle);
            if (shortest_segment_from_projection.end.on(arc)) {
                return [dist_from_projection, shortest_segment_from_projection];
            }
        }
        /* Case 3. Otherwise closest point is one of the end points of the segment */
        let dist_and_segment = [];
        dist_and_segment.push(Distance.point2arc(seg.start, arc));
        dist_and_segment.push(Distance.point2arc(seg.end, arc));

        let dist_tmp, segment_tmp;
        [dist_tmp, segment_tmp] = Distance.point2segment(arc.start, seg);
        dist_and_segment.push([dist_tmp, segment_tmp.reverse()]);

        [dist_tmp, segment_tmp] = Distance.point2segment(arc.end, seg);
        dist_and_segment.push([dist_tmp, segment_tmp.reverse()]);

        Distance.sort(dist_and_segment);
        return dist_and_segment[0];
    }

    /**
     * Calculate distance and shortest segment between two circles
     * @param circle1
     * @param circle2
     * @returns {Number | Segment} - distance and shortest segment
     */
    static circle2circle(circle1, circle2) {
        let ip = circle1.intersect(circle2);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        // Case 1. Concentric circles. Convert to arcs and take distance between two arc starts
        if (circle1.center.equalTo(circle2.center)) {
            let arc1 = circle1.toArc();
            let arc2 = circle2.toArc();
            return Distance.point2point(arc1.start, arc2.start);
        } else {
            // Case 2. Not concentric circles
            let line = new Flatten.Line(circle1.center, circle2.center);
            let ip1 = line.intersect(circle1);
            let ip2 = line.intersect(circle2);

            let dist_and_segment = [];

            dist_and_segment.push(Distance.point2point(ip1[0], ip2[0]));
            dist_and_segment.push(Distance.point2point(ip1[0], ip2[1]));
            dist_and_segment.push(Distance.point2point(ip1[1], ip2[0]));
            dist_and_segment.push(Distance.point2point(ip1[1], ip2[1]));

            Distance.sort(dist_and_segment);
            return dist_and_segment[0];
        }
    }

    /**
     * Calculate distance and shortest segment between two circles
     * @param circle
     * @param line
     * @returns {Number | Segment} - distance and shortest segment
     */
    static circle2line(circle, line) {
        let ip = circle.intersect(line);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        let [dist_from_center, shortest_segment_from_center] = Distance.point2line(circle.center, line);
        let [dist, shortest_segment] = Distance.point2circle(shortest_segment_from_center.end, circle);
        shortest_segment = shortest_segment.reverse();
        return [dist, shortest_segment];
    }

    /**
     * Calculate distance and shortest segment between arc and line
     * @param arc
     * @param line
     * @returns {Number | Segment} - distance and shortest segment
     */
    static arc2line(arc, line) {
        /* Case 1 Line and arc intersected. Return the first point and zero distance */
        let ip = line.intersect(arc);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        let circle = new Flatten.Circle(arc.center, arc.r);

        /* Case 2. Distance to projection of center point to line bigger than radius AND
         * projection point belongs to segment AND
           * distance from projection point to circle belongs to arc  =>
           * return this distance from projection to circle */
        let [dist_from_center, shortest_segment_from_center] = Distance.point2line(circle.center, line);
        if (Flatten.Utils.GE(dist_from_center, circle.r)) {
            let [dist_from_projection, shortest_segment_from_projection] =
                Distance.point2circle(shortest_segment_from_center.end, circle);
            if (shortest_segment_from_projection.end.on(arc)) {
                return [dist_from_projection, shortest_segment_from_projection];
            }
        } else {
            let dist_and_segment = [];
            dist_and_segment.push(Distance.point2line(arc.start, line));
            dist_and_segment.push(Distance.point2line(arc.end, line));

            Distance.sort(dist_and_segment);
            return dist_and_segment[0];
        }
    }

    /**
     * Calculate distance and shortest segment between arc and circle
     * @param arc
     * @param circle2
     * @returns {Number | Segment} - distance and shortest segment
     */
    static arc2circle(arc, circle2) {
        let ip = arc.intersect(circle2);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        let circle1 = new Flatten.Circle(arc.center, arc.r);

        let [dist, shortest_segment] = Distance.circle2circle(circle1, circle2);
        if (shortest_segment.start.on(arc)) {
            return [dist, shortest_segment];
        } else {
            let dist_and_segment = [];

            dist_and_segment.push(Distance.point2circle(arc.start, circle2));
            dist_and_segment.push(Distance.point2circle(arc.end, circle2));

            Distance.sort(dist_and_segment);

            return dist_and_segment[0];
        }
    }

    /**
     * Calculate distance and shortest segment between two arcs
     * @param arc1
     * @param arc2
     * @returns {Number | Segment} - distance and shortest segment
     */
    static arc2arc(arc1, arc2) {
        let ip = arc1.intersect(arc2);
        if (ip.length > 0) {
            return [0, new Flatten.Segment(ip[0], ip[0])];
        }

        let circle1 = new Flatten.Circle(arc1.center, arc1.r);
        let circle2 = new Flatten.Circle(arc2.center, arc2.r);

        let [dist, shortest_segment] = Distance.circle2circle(circle1, circle2);
        if (shortest_segment.start.on(arc1) && shortest_segment.end.on(arc2)) {
            return [dist, shortest_segment];
        } else {
            let dist_and_segment = [];

            let dist_tmp, segment_tmp;

            [dist_tmp, segment_tmp] = Distance.point2arc(arc1.start, arc2);
            if (segment_tmp.end.on(arc2)) {
                dist_and_segment.push([dist_tmp, segment_tmp]);
            }

            [dist_tmp, segment_tmp] = Distance.point2arc(arc1.end, arc2);
            if (segment_tmp.end.on(arc2)) {
                dist_and_segment.push([dist_tmp, segment_tmp]);
            }

            [dist_tmp, segment_tmp] = Distance.point2arc(arc2.start, arc1);
            if (segment_tmp.end.on(arc1)) {
                dist_and_segment.push([dist_tmp, segment_tmp.reverse()]);
            }

            [dist_tmp, segment_tmp] = Distance.point2arc(arc2.end, arc1);
            if (segment_tmp.end.on(arc1)) {
                dist_and_segment.push([dist_tmp, segment_tmp.reverse()]);
            }

            [dist_tmp, segment_tmp] = Distance.point2point(arc1.start, arc2.start);
            dist_and_segment.push([dist_tmp, segment_tmp]);

            [dist_tmp, segment_tmp] = Distance.point2point(arc1.start, arc2.end);
            dist_and_segment.push([dist_tmp, segment_tmp]);

            [dist_tmp, segment_tmp] = Distance.point2point(arc1.end, arc2.start);
            dist_and_segment.push([dist_tmp, segment_tmp]);

            [dist_tmp, segment_tmp] = Distance.point2point(arc1.end, arc2.end);
            dist_and_segment.push([dist_tmp, segment_tmp]);

            Distance.sort(dist_and_segment);

            return dist_and_segment[0];
        }
    }

    /**
     * Calculate distance and shortest segment between point and polygon
     * @param point
     * @param polygon
     * @returns {Number | Segment} - distance and shortest segment
     */
    static point2polygon(point, polygon) {
        let min_dist_and_segment = [Number.POSITIVE_INFINITY, new Flatten.Segment()];
        for (let edge of polygon.edges) {
            let [dist, shortest_segment] = (edge.shape instanceof Flatten.Segment) ?
                Distance.point2segment(point, edge.shape) : Distance.point2arc(point, edge.shape);
            if (Flatten.Utils.LT(dist, min_dist_and_segment[0])) {
                min_dist_and_segment = [dist, shortest_segment];
            }
        }
        return min_dist_and_segment;
    }

    static shape2polygon(shape, polygon) {
        let min_dist_and_segment = [Number.POSITIVE_INFINITY, new Flatten.Segment()];
        for (let edge of polygon.edges) {
            let [dist, shortest_segment] = shape.distanceTo(edge.shape);
            if (Flatten.Utils.LT(dist, min_dist_and_segment[0])) {
                min_dist_and_segment = [dist, shortest_segment];
            }
        }
        return min_dist_and_segment;
    }

    /**
     * Calculate distance and shortest segment between two polygons
     * @param polygon1
     * @param polygon2
     * @returns {Number | Segment} - distance and shortest segment
     */
    static polygon2polygon(polygon1, polygon2) {
        let min_dist_and_segment = [Number.POSITIVE_INFINITY, new Flatten.Segment()];
        for (let edge1 of polygon1.edges) {
            for (let edge2 of polygon2.edges) {
                let [dist, shortest_segment] = edge1.shape.distanceTo(edge2.shape);
                if (Flatten.Utils.LT(dist, min_dist_and_segment[0])) {
                    min_dist_and_segment = [dist, shortest_segment];
                }
            }
        }
        return min_dist_and_segment;
    }

    /**
     * Returns [mindist, maxdist] array of squared minimal and maximal distance between boxes
     * Minimal distance by x is
     *    (box2.xmin - box1.xmax), if box1 is left to box2
     *    (box1.xmin - box2.xmax), if box2 is left to box1
     *    0,                       if box1 and box2 are intersected by x
     * Minimal distance by y is defined in the same way
     *
     * Maximal distance is estimated as a sum of squared dimensions of the merged box
     *
     * @param box1
     * @param box2
     * @returns {Number | Number} - minimal and maximal distance
     */
    static box2box_minmax(box1, box2) {
        let mindist_x = Math.max(Math.max(box1.xmin - box2.xmax, 0), Math.max(box2.xmin - box1.xmax, 0));
        let mindist_y = Math.max(Math.max(box1.ymin - box2.ymax, 0), Math.max(box2.ymin - box1.ymax, 0));
        let mindist = mindist_x * mindist_x + mindist_y * mindist_y;

        let box = box1.merge(box2);
        let dx = box.xmax - box.xmin;
        let dy = box.ymax - box.ymin;
        let maxdist = dx * dx + dy * dy;

        return [mindist, maxdist];
    }

    static minmax_tree_process_level(shape, level, min_stop, tree) {
        // Calculate minmax distance to each shape in current level
        // Insert result into the interval tree for further processing
        // update min_stop with maxdist, it will be the new stop distance
        let mindist, maxdist;
        for (let node of level) {

            // [mindist, maxdist] = Distance.box2box_minmax(shape.box, node.max);
            // if (Flatten.Utils.GT(mindist, min_stop))
            //     continue;

            // Estimate min-max dist to the shape stored in the node.item, using node.item.key which is shape's box
            [mindist, maxdist] = Distance.box2box_minmax(shape.box, node.item.key);
            if (node.item.value instanceof Flatten.Edge) {
                tree.insert([mindist, maxdist], node.item.value.shape);
            } else {
                tree.insert([mindist, maxdist], node.item.value);
            }
            if (Flatten.Utils.LT(maxdist, min_stop)) {
                min_stop = maxdist;                       // this will be the new distance estimation
            }
        }

        if (level.length === 0)
            return min_stop;

        // Calculate new level from left and right children of the current
        let new_level_left = level.map(node => node.left.isNil() ? undefined : node.left).filter(node => node !== undefined);
        let new_level_right = level.map(node => node.right.isNil() ? undefined : node.right).filter(node => node !== undefined);
        // Merge left and right subtrees and leave only relevant subtrees
        let new_level = [...new_level_left, ...new_level_right].filter(node => {
            // Node subtree quick reject, node.max is a subtree box
            let [mindist, maxdist] = Distance.box2box_minmax(shape.box, node.max);
            return (Flatten.Utils.LE(mindist, min_stop));
        });

        min_stop = Distance.minmax_tree_process_level(shape, new_level, min_stop, tree);
        return min_stop;
    }

    /**
     * Calculates sorted tree of [mindist, maxdist] intervals between query shape
     * and shapes of the planar set.
     * @param shape
     * @param set
     */
    static minmax_tree(shape, set, min_stop) {
        let tree = new IntervalTree();
        let level = [set.index.root];
        let squared_min_stop = min_stop < Number.POSITIVE_INFINITY ? min_stop * min_stop : Number.POSITIVE_INFINITY;
        squared_min_stop = Distance.minmax_tree_process_level(shape, level, squared_min_stop, tree);
        return tree;
    }

    static minmax_tree_calc_distance(shape, node, min_dist_and_segment) {
        let min_dist_and_segment_new, stop;
        if (node != null && !node.isNil()) {
            [min_dist_and_segment_new, stop] = Distance.minmax_tree_calc_distance(shape, node.left, min_dist_and_segment);

            if (stop) {
                return [min_dist_and_segment_new, stop];
            }

            if (Flatten.Utils.LT(min_dist_and_segment_new[0], Math.sqrt(node.item.key.low))) {
                return [min_dist_and_segment_new, true];   // stop condition
            }

            let [dist, shortest_segment] = Distance.distance(shape, node.item.value);
            // console.log(dist)
            if (Flatten.Utils.LT(dist, min_dist_and_segment_new[0])) {
                min_dist_and_segment_new = [dist, shortest_segment];
            }

            [min_dist_and_segment_new, stop] = Distance.minmax_tree_calc_distance(shape, node.right, min_dist_and_segment_new);

            return [min_dist_and_segment_new, stop];
        }

        return [min_dist_and_segment, false];
    }

    /**
     * Calculates distance between shape and Planar Set of shapes
     * @param shape
     * @param {PlanarSet} set
     * @param {Number} min_stop
     * @returns {*}
     */
    static shape2planarSet(shape, set, min_stop = Number.POSITIVE_INFINITY) {
        let min_dist_and_segment = [min_stop, new Flatten.Segment()];
        let stop = false;
        if (set instanceof Flatten.PlanarSet) {
            let tree = Distance.minmax_tree(shape, set, min_stop);
            [min_dist_and_segment, stop] = Distance.minmax_tree_calc_distance(shape, tree.root, min_dist_and_segment);
        }
        return min_dist_and_segment;
    }

    static sort(dist_and_segment) {
        dist_and_segment.sort((d1, d2) => {
            if (Flatten.Utils.LT(d1[0], d2[0])) {
                return -1;
            }
            if (Flatten.Utils.GT(d1[0], d2[0])) {
                return 1;
            }
            return 0;
        });
    }

    static distance(shape1, shape2) {
        return shape1.distanceTo(shape2);
    }
}

Flatten.Distance = Distance;
